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17CommentsBattle Ground WAJoined August 1st, 2015
BSEE from California State University Sacremento - Electrical/Electronic Engineer-1997 Worked at Underwriters Laboratories Inc. Since 1997, retired 2015. Title: Staff Engineer - industries of Audio Equipment and Information Technology Equipment
  • Eee1997 commented on TueBjørn's instructable 100W LED - Flashlight3 days ago
    100W LED - Flashlight

    100% correct.If we want to employ Lithium battery cells we really need to know what we are doing. These cells have been known to explode or burst into extremely hot flames if misused.

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  • LM317 Based DIY Variable Benchtop Power Supply

    Thank you for your question. Assuming that the SMPS is one of the type used for building-in to computers or other end products. Power supplies such as these may have been evaluated by safety agencies but the safety investigation in most cases is not complete unless they are designated as “Listed ITE Product”. In the case of non-Listed supply (i.e. UL Recognized) there are certain Conditions of Acceptibility (CoA) that must be addressed in the end product. Basically, the CoA’s address shock, fire, mechanical and energy hazards. There may be others such as excessive heat.An energy hazard exists when the available voltage and current exceeds a level that may cause an explosive result if the output of the source was to be shorted. This level is defined in standard fo...

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    Thank you for your question. Assuming that the SMPS is one of the type used for building-in to computers or other end products. Power supplies such as these may have been evaluated by safety agencies but the safety investigation in most cases is not complete unless they are designated as “Listed ITE Product”. In the case of non-Listed supply (i.e. UL Recognized) there are certain Conditions of Acceptibility (CoA) that must be addressed in the end product. Basically, the CoA’s address shock, fire, mechanical and energy hazards. There may be others such as excessive heat.An energy hazard exists when the available voltage and current exceeds a level that may cause an explosive result if the output of the source was to be shorted. This level is defined in standard for safety UL/CSA/IEC 60950 as 240VA. Such a hazard may result in blindness or severe burns. As you may know, a supply of <36vdc may not be a shock hazard but if it’s capable of delivering >6.67Amps (36x6.67=240) it’s now an energy hazard. It is the general consensus between the US, CA, EU and other countries that any source exceeding the 240VA limits shall not be made accessible to an end user.Best regards, I hope this helps.

    Correction, please delete the less than sign “<“ on the 36vdc above.FYI, anything <60vdc and double/reinforced insulation provided between ac mains (hazardous voltage) is not considered a shock hazard. Some exceptions apply.Thank you.

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  • LM317 Based DIY Variable Benchtop Power Supply

    This project uses a switch mode power supply (SMPS). Most of these powers supplies have been evaluated by safety certification agencies such as UL, CSA, TUV etc. I do not recommend using a supply that has not been. They should bear the Mark on the outer enclosure of the SMPS. Such power supplies are evaluated to UL/CSA/IEC 60950 standard. This assures that the dc output of the SMPS is isolated from ac mains by reinforced insulation but may not always be the case. Always obtain and read the Conditions of Acceptibility of the specific smps you are employing to be sure and that the output dc voltage is Safety Extra Low Volgage (SELV). Anything else is not intended to be accessible and and may present a shock hazard. The dc output energy should also be limited to 240VA.Notes: Do not...

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    This project uses a switch mode power supply (SMPS). Most of these powers supplies have been evaluated by safety certification agencies such as UL, CSA, TUV etc. I do not recommend using a supply that has not been. They should bear the Mark on the outer enclosure of the SMPS. Such power supplies are evaluated to UL/CSA/IEC 60950 standard. This assures that the dc output of the SMPS is isolated from ac mains by reinforced insulation but may not always be the case. Always obtain and read the Conditions of Acceptibility of the specific smps you are employing to be sure and that the output dc voltage is Safety Extra Low Volgage (SELV). Anything else is not intended to be accessible and and may present a shock hazard. The dc output energy should also be limited to 240VA.Notes: Do not rely on the internal current limit of the SMPS. This is considered a abnormal condition and should not be relied upon by the end product.If SMPS requires protective Earth Ground make sure it is reliably connected to the grounding pin of the power cord and so is your metal enclosure.

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  • Eee1997 commented on dave5201's instructable How To Hide a Wall Wart Transformer10 months ago
    How To Hide a Wall Wart Transformer

    Additional Safety Warnings- NEC Article (300) cautions against mixing low voltage circuits and AC primary (120V) in the same electrical box or inside walls for that matter. Although there may be some acception by Article 300.3 C if certain conditions are met, mixing of these circuits may be against code altogether in some jurisdictions. Please also note there are restrictions on running high and low voltage circuits in parallel (touching together) inside walls. They should be separated by at least 6 inches. Not adhering to these guidelines may increase possibility of fire and electrical shock hazards.In regard to performance, you may run into interference problems when ac lines and low voltage lines used for tv, phones, audio equipment, etc. are ran closely together.

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  • Eee1997 commented on MicahS23's instructable Wood Beam Fireplace Mantel11 months ago
    Wood Beam Fireplace Mantel

    Nice work! Special thanks for info on fire safety.

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  • Eee1997 commented on darthwolf's instructable A Simple Bench Variable Power Supply11 months ago
    A Simple Bench Variable Power Supply

    The type power supply used for this project is what called a switch mode power supply abrieviated (SMPS). The outputs of these supplies are usually very well regulated by means of a feedback loop from the secondary to the controlling IC located in the primary circuit. Regulation is achieved by pulse width modulation (PWM) of the primary side winding. In most cases the +/-12v, and 5V and others are regulated independently. I do not believe I have ever seen a follower configuration. But that does not mean you will never come across one. Sometimes the 5V are regulated down from the 12v winding, but I would not like to speculate here. It depends on the power supply manufacture and type you are using. To know for sure, one would have to take a look at the power supply schematic to de...

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    The type power supply used for this project is what called a switch mode power supply abrieviated (SMPS). The outputs of these supplies are usually very well regulated by means of a feedback loop from the secondary to the controlling IC located in the primary circuit. Regulation is achieved by pulse width modulation (PWM) of the primary side winding. In most cases the +/-12v, and 5V and others are regulated independently. I do not believe I have ever seen a follower configuration. But that does not mean you will never come across one. Sometimes the 5V are regulated down from the 12v winding, but I would not like to speculate here. It depends on the power supply manufacture and type you are using. To know for sure, one would have to take a look at the power supply schematic to determine how the outputs are regulated. Hope this helps.

    The 12V1 and 12V2 notation indicates that there are (2) 12v outputs. 12V1 differs from 12V2 in that they are derived from separated secondary winding of the isolating transformer. They are intended for different functions as specified in the end product and generally will have different current ratings. One may find some supplies with more than two. For example, 12Vn where n is any integer (1,2,3...).

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  • Eee1997 commented on darthwolf's instructable A Simple Bench Variable Power Supply11 months ago
    A Simple Bench Variable Power Supply

    hello,You are correct there are current limit built into these power supplies per the specifications of there customers. The current limits however are in most cases much higher than you need or too high for safe accessibility of the end user. For example, many power supplies may have a current limit on a 5 vdc line in excess on 30 amps. This is not only a fire hazard but also an energy hazard. You will find these that this information is documented in the Conditions of Acceptability (COA's) for the specific power supply you are using. The COA's are not standard. Each specific model will have their own COA's. These type power supplies are for building-in high power computer products and are not considered safe until the Conditions of Acceptibility have been addresses in the e...

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    hello,You are correct there are current limit built into these power supplies per the specifications of there customers. The current limits however are in most cases much higher than you need or too high for safe accessibility of the end user. For example, many power supplies may have a current limit on a 5 vdc line in excess on 30 amps. This is not only a fire hazard but also an energy hazard. You will find these that this information is documented in the Conditions of Acceptability (COA's) for the specific power supply you are using. The COA's are not standard. Each specific model will have their own COA's. These type power supplies are for building-in high power computer products and are not considered safe until the Conditions of Acceptibility have been addresses in the end product. Overvoltage has been tested and safe during the power supply safety investigation and is not usually ap problem for the end product. However, there may be units that have low voltage output such as 5vdc and are not considered SELV. They may only be ELV. The difference here is ELV does not have reinforced insulation from ac mains. Again, the COA's will give you this information. Reference Standard for safety IEC/UL/CSA 60950 for more details. Thank you.

    Please also note: These power supplies are not intended for use as a stand alone power source. They are intended for building-in to an end product and must have a proper fire and electrical enclosure. The specifications such as V,A,Watts available energy of the outputs are dictated by the end product manufacture to the power supply manufacturer for their specific needs for custom product such as a computer. These power supplies may not be safe for your specific application. They require additional attention to potential hazards depending on your specific use and construction. Before tying outputs together in order to double voltage, I recommend that you have high level knowledge and expertice with these type power supplies, obtain schematic diagrams and have necessary skills to do so.

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  • Eee1997 commented on darthwolf's instructable A Simple Bench Variable Power Supply11 months ago
    A Simple Bench Variable Power Supply

    please also note. Most of these power supplies will have 2 5vdc ratings and they are not relative to one another. Typically one of these outputs will have a much lower current rating and is derived from an independent secondary winding of the transformer. Therefore you do not want to combine these 2 outputs in series to get 10 vdc. The return paths may not be the same. One of these two outputs are noted as 5vsb or stand-by. This one will always be active when the front stand-by switch is on or off.

    I would like to clarify what is meant by VA. It is very similar to wattage. It is the product of volts times amps. Each output has a volt, current and a VA rating. VA is an energy rating of the output. For example, 12vdc output capable of 20 amps is 240 VA.

    As an electronic engineer with 35 years experience in implementation and design of these power supplies (PS) in various end products, I would like to voice some important safety concerns with this design. First of all it is important to know the current and VA ratings of each DC output. They should never be exceeded. Anything over 240 VA (volt/amps) is considered enough energy to create an energy hazard and should not be accessible to the user. Even if it's only 5vdc. Any current over 8 amps for 60 sec has enough energy to present a fire hazard in the end product if there is a component failure. Many of these type PS exceed these limits and must be addressed in the end product design. Secondly, the current rating of each output should never be exceeded. This can be complex beca...

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    As an electronic engineer with 35 years experience in implementation and design of these power supplies (PS) in various end products, I would like to voice some important safety concerns with this design. First of all it is important to know the current and VA ratings of each DC output. They should never be exceeded. Anything over 240 VA (volt/amps) is considered enough energy to create an energy hazard and should not be accessible to the user. Even if it's only 5vdc. Any current over 8 amps for 60 sec has enough energy to present a fire hazard in the end product if there is a component failure. Many of these type PS exceed these limits and must be addressed in the end product design. Secondly, the current rating of each output should never be exceeded. This can be complex because many of these supplies may be at max total rating with only 2 of the outputs at rated load. In addition, the ventilation holes on the PS should not be blocked or restricted as with the front holes in your design. Overloading and over heating of the power transformer will degrade the protective insulation and may result in fire or shock hazard. Openings on the top if larger than 4 mm are not allowed by safety agencies such as UL, CSA, TUV unless they are situated within the end product where entry of objects are not possible. Although these PS may carry UL/CSA/TUV recognition they are required to be inspected a second time before an end product may be labeled with safety certification Marks. I recommend that you obtain the Conditions of Acceptibility from the manufacture of the PS so you know what you are dealing with.

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  • Eee1997 commented on TheCutlassKid's instructable LED "Vacuum" Tubes1 year ago
    LED "Vacuum" Tubes

    I have found mercury tubes in various vintage shops. They are very interesting in their size, shape and design and can be tempting to the unexpecting artist. In regard to Barium, it is found in abundance in nature however it can be harmful to humans depending on the exposure they may have. People with the greatest risk to barium exposure with additional health effects are those that work with barium. Most of the health risks that they can undergo are caused by breathing in air that contains barium sulphate or barium carbonate.Many hazardous waste sites contain certain amounts of barium. People that live near them may be exposed to harmful levels. The exposure will than be caused by breathing dust, eating soil or plants, or drinking water that is polluted with barium. Skin contact may...

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    I have found mercury tubes in various vintage shops. They are very interesting in their size, shape and design and can be tempting to the unexpecting artist. In regard to Barium, it is found in abundance in nature however it can be harmful to humans depending on the exposure they may have. People with the greatest risk to barium exposure with additional health effects are those that work with barium. Most of the health risks that they can undergo are caused by breathing in air that contains barium sulphate or barium carbonate.Many hazardous waste sites contain certain amounts of barium. People that live near them may be exposed to harmful levels. The exposure will than be caused by breathing dust, eating soil or plants, or drinking water that is polluted with barium. Skin contact may also occur.The health effects of barium depend upon the water-solubility of the compounds. Barium compounds that dissolve in water can be harmful to human health. The uptake of continuous amounts of barium that is water-soluble may cause paralyses and in some cases even death.Small amounts of water-soluble barium may cause a person to experience breathing difficulties, increased blood pressures, heart rhythm changes, stomach irritation, muscle weakness, changes in nerve reflexes, swelling of brains and liver, kidney and heart damage.I don't mean to sound so paranoid but the chemicals used in these devices were never intended to be accessible to humans when they were maid back in the early half of 20th century. I am curious what people are using to power the LEDs. There is a whole other list of dangers when using Lithium cell batteries.

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  • Eee1997 commented on TheCutlassKid's instructable LED "Vacuum" Tubes1 year ago
    LED "Vacuum" Tubes

    This is a cool idea, but please beware. Some of these old tube are infused with mercury vapor gas which is an extremely toxic nasty gas. Make sure you know what is inside before you crack it open.

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  • Eee1997 commented on licheness's instructable LED Cork Light1 year ago
    LED Cork Light

    if you are building this project, please be aware of the extreme danger these batteries present espicially when they are easily accessible. For more details please see:http://www.kidsafeqld.com.au/index.php/news/85-button-batteries-a-hidden-danger

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